Pianopobte



CHAS. GLASSBOROIV, OF PHILADELPHIA, PENNSYLVANIA.

PIANOFORTE.

Specicaton of Letters Patent No. 24,865, dated July 26, 1859.

To all whom 'it may concern:

Be it known that I, CHARLES GLAssoRow, of the city and county of Philadelphia and State of Pennsylvania, have invented a new and useful Improvement in Pianos; and I do hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying dra-wing and to the letters of reference marked thereon.

My invention relates to an improvement in that class of pianos generally termed upright or cabinet pianos,7 the strings of which are arranged either perpendicular-ly or obliquely in a vertical instead of horizontal plane as in square or grand pianos.

My improvement consists in constructing the frame of an upright piano with two complete pin and bottom blocks with suitable attachments for receiving` two distinct sets of strings, and two complete sounding boards, connected together at suit-able intervals as more fully described hereafter.

The objects of my invention are, l'irstly, to equalize the strain on both sides of the frame so that the latter may be made much lighter than usual and so that the instrument may be maintained in tune longer than is usual in upright pianos. Secondly, to increase the volume of the tone by tuning the strings on one side to the same pitch as those on the opposite side of the frame, the vibration imparted by the hammer to one string being communicated to the string of the same pitch on the opposite side. Thirdly, to prevent the sounding boards from sinking in the middle.

In order to enable others skilled in the manufacture of pianos to make and use my invention, I will now proceed to describe its construction.

On reference to the accompanying drawing which forms a part of this specification-Figure l, represents a front view of a portion of the framework of an upright piano; Fig. 2, an end view of Fig. l; Fig. 8, a sectional view, and Fig. t, a plan view.

Similar letters refer to similar parts throughout the several views.

In ordinary upright pianos it is usual to attach the strings to one side only of the string frame, the latter being' made of strong and substantial beams firmly secured together. The strings by their excessive strain are apt to spring the frame out of shape so as to render it a matter of difficulty to maintain the instrument in proper tune for any length of time, especially when it is used in warm and variable climates. This evil may certainly be partially remedied by making the frame more massive and strong but only at a sacrifice of the mellowness and volume of the tone. My improvement has been designed more especially for the purpose of obviating the above di'diculties.

A, and A, are two pin blocks situated directly opposite to and in a line with each other and firmly secured to the end beams of the frame as well as to suitable intermediate beams G.

B, and B', are the bottom blocks also secured to the end and intermediate beams of the frame, and to each of these bot-tom blocks as well as to other beams of the frame is secured a diagonal or a curved beam C.

Each pin block is furnished with the requisite number of tuning pins a., around each of which a string is coiled as usual, the lower ends of the strings being attached to pins on the bottom block B, or on the diagonal beam C, according to the position each spring occupies in the set. To each pin block is secured the usual bridge piece Z1, over which the strings pass and on which they bear, the strings being retained in their proper position on the bridge by suitable pins.

Between the pin blocks and the bottom blocks are situated the sounding boards D, D, one on each side of the frame, the boards resting on ledges formed on the pinand bottom blocks, so as to be the requisite distance from the strings. .Each sounding board has the usual bridge piece E, the latter having pins to retain the strings in their proper position. The two sounding boards are connected together by stay bolts F, placed at suitable intervals, the ends of the bolts passing through the boards as well as through the bridge pieces E, and being securely fastened to both by suitable nuts.

It will now be seen without further description that there are two complete sets of strings and two complete sounding boards on one frame, the strings on one side being of similar material and ofthe same strength as those on the opposite side. In tuning the instrument it is necessary that the corresponding strings on the opposite side should be tuned to the same pitch, and inasmuch as the corresponding strings are of similar material they must have exactly the same tension imparted to them, consequently the strain on one side of the frame will be eX- actly equal to that on the other. By this arrangement the massive frame used in this class of instruments to the injury of the tone, as well as the usual cumbrous braces,

may be dispensed with, and a frame comv posed of light materials and occupying but little space, may be substituted, at the same time, the strain being equal on both sides, the instrument may be maintained in tune much longer than when the strings and consequently the strain, are on one side of the frame only. Another advantage gained by this arrangement is the facility with which the sounding` boards may be connected together so that the pressure of the strings on one board is neutralized by the pressure of the strings on the other board, both boards are thus prevented from sinking in the middle and warping. In addition to the improvement in the tone gained by the substitution of a light for a massive and heavy frame the volume of the tone is increased by the use of the two sets of strings, for although but one set of strings be operated upon by the action of the keys it will be evidet that the moment one of the strings on one side is sounded the string -of a corresponding pitch on the opposite side will give out a mellow and prolonged sound, which will add to the volume and power of the instruments tone.

I claim as my invention and desire to secure by Letters Patent- Constructing the string frame of an upright piano with two pin blocks and other appliances for receiving two sets of Strings, and two distinct sounding boards, the strings being arranged one set on one side and the other set on the opposite side of the frame, the two sounding boards being connected together, and the whole being otherwise constructed substantially in the man ner and for the purpose herein set forth.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

CHARLES GLASSBOROVVc IVitnesses:

HENRY HowsoN, CHARLES D. FREEMAN. 

